Prodigal Sons
by slipstream
Summary: Self care is using alien technology to rip holes in the fabric of the known multiverse, kidnapping all of the overworked, underappreciated alternate versions of yourself, and standing by while your loving family tucks them forcefully into bed. (2k14, 2k12, 2k7 crossover)


_Inspired by this genius post from hotmilkytea: tinyurl DOT com SLASH_ _z8f6u9h . Because trans-dimensional kidnapping is the obvious solution for underappreciated Donatellos._

* * *

"No," says Leo. "Absolutely not."

"But _Leo!_ " Mikey protests. "You saw how they were treating him!"

" _Them_ ," Raph corrects. He's got Donnie—not _their_ Donnie, some _other_ Donnie, one who shares his affinity for headsets but not pants or skirts or apparently clothing in general—tucked under one arm and doesn't seem willing to put him down any time soon. With the exception of the occasional, world-weary sigh, Other Donnie seems more or less resigned to the turtle-handling, limbs limp and bloodshot eyes half-hooded with exhaustion as he watches the argument unfold. "They don't appreciate him. _Shit_ , did you see how rough Biker Me was riding? _Guarantee_ you he's never given that bike so much as an oil change, let alone rebuilt the engine block after a trashing like that. And those other guys..."

He shakes his head, at a loss for words. The less said about that other dimension, the better.

Leo's scowl softens slightly. It wasn't all that hard to begin with—the familiar scars and creases of his face washed out by the pink, pulsing light of the twin triangular portals—and Mikey spots a window of opportunity. He seizes the _other_ other Donnie—the three-toed one with a head like a bean—by the shoulders and thrusts him up towards his oldest brother.

"Just _look_ at him!" he says, giving the now-squawking and kicking Donnie a little shake. "Have you ever seen anything so _sad_ and _pitiful_ and— _ow!_ "

"He bit you," Leo observes dryly as Mikey shakes out the injured digit, a warm note of approval creeping into his voice. Other Other Donnie has already retreated to the relative safety beside Donnie— _their_ Donnie, this time, eyes huge and slightly crossed behind his glasses as he looks first at the portals, then at his alternate selves, then to the increasingly complex swirl of numbers and diagrams on his holo display, then back to the portals again.

"I can do more than bite," hisses Other Other Donnie, bo at the ready and pupils obscured by the white membrane of his third eyelid. "Promise you that."

"Can you tell me how the _heck_ these things work and how to keep them from collapsing?" Donnie asks frantically. "Because if my calculations are correct then—!"

There's a flash of light, followed by the electric sizzle and burnt ozone smell of frying circuits, and the two portals disappear with a comically anticlimactic _pop_.

"—that," Donnie sighs. "That will happen." With a gesture he minimizes his display and bends to scoop up the two faintly smoking metal discs wobbling lazily across the cracked concrete. He lifts one, then the other up to eye level for closer inspection, tongue out and brow furrowed in concentration as his fingers work at the seams of the now-darkened hexagons, before shrugging and holding them out to his counterparts. "Uh, you wouldn't happen to know how to fix these, would you?"

"No clue," says Other Donnie.

"Yes," says Other Other Donnie. "Well, sort of."

Leo groans, head falling back to thump against his shell. Raph clutches Other Donnie a little tighter, and Other Donnie finally starts to squirm, building-block teeth bared nervously as he catches sight of Raph's manically boyish grin.

To his credit, once Raph catches on to Other Donnie's discomfort, he sets him down with a hasty, hilariously blubbering apology.

"We're _not_ keeping them," Leo reiterates as they turn their steps back towards the Lair. "This is just a temporary thing until we figure out how to get them home."

"Right," Mikey says, already planning out where they'll sleep and how to best portion the week's meals for seven instead of five.

* * *

At least they get the name situation sorted out relatively quickly. They all agree that it'd be far too confusing for any one of them to lay claim to their full given name. As the native to this particular dimension, for the sake of simplicity their Donatello gets to the two-syllable nickname they've called him since they learned how to talk. The Donatello they pulled from the universe where Leo bears a striking resemblance to Donald Duck doesn't put up much of a fight for it, shrugging and admitting that he's preferred Don for a while now. The high-strung, red-eyed Donatello reluctantly agrees to go by Dee for the time being, but not without some grumbling.

"Good luck to the next bunch of Donatellos you guys decide to kidnap. At least I get dibs on the _first_ letter. I just feel sorry for the two saps who have to fight it out for the L, let alone the sucker stuck with _H_ , or—"

"You spell Donatello with an _H_?" Mikey interrupts. "Like, at the end? That's weird." The multiverse is apparently stranger than he realized.

" _Mikey_ ," Leo shushes in his best _if-you-can't-say-anything-nice-don't-say-anything-at-all_ tone.

"H as in _Hamato_ ," Dee clarifies with scowl.

"Ham-an'-Tomato- _wha_?"

This draws a bemused frown from Don. "As in... Hamato Yoshi? Y'know, Splinter's master from Japan?"

Now it's Dee's turn to look confused. "What? No, Master Splinter _is_ Hamato Yoshi."

Don scoffs in disbelief. "We're talking about the giant rat that raised us in the art of ninjitsu, right?" At Dee's nod, he continues. "So how would that even _work?_ Did he just... _turn_ into a rat one day?"

"Of course," says Dee. " _Duh_. How else would a rat know martial arts?"

"You'd be surprised," Leo mutters. "Okay, heads up, the last tunnel's a bit of a ride."

The new guys are less than enthusiastic about getting wet, which completely baffles Mikey given that they've got the least amount of gear to dry off. Master Splinter is waiting for them at the splash-down pool, comfortably seated in the lotus position with his hands tucked meditatively into his opposing sleeves.

"Welcome home, my sons, and—" His whiskers perk forward abruptly as two more purple-masked heads emerge from the water. "—my sons?"

"Long story," Donnie says, shaking some of the water from his boots. "Short version goes something like this: mysterious bad guys, creepy abandoned warehouse, experiments with alien technology, portals to other dimensions, encounters with alternate selves, alternate selves in mortal peril, yada yada yada, alternate selves pulled into home dimension in Hail Mary pass to keep matrix of known multiverse from collapsing, unfortunate twist of circumstance trapping said alternate selves here for the time being."

"Plus," Mikey adds, "these dudes were getting the short end of the ninja stick from _our_ douchebag alternate selves, and we really, _really_ thought they'd be better off with us."

Raph and Leo elbow him in the sides simultaneously, which hurts, but not as much as the uncomfortable shuffling of feet from Don and Dee. God, Mikey just wants to hug them both _so hard_. It's worse than those Sarah McLachlan commercials by far.

"Hmm..." Pushing himself to his feet, Splinter peers into each of their faces in turn before turning his attention to their bare limbs, their sparse gear, the broad flair of their wrists and ankles, the thick plating spanning the gap between shell and plastron. His black eyes are hard, glittering, and inscrutable. "These must be strange universes, indeed."

"Not _that_ strange," Dee huffs, though a note of doubt edges in as he turns to the shorter of his alternate selves. "Right, Don?"

Don grimaces.

"As to the claim that your own alternate selves are, and I quote, ' _douchebags_ '—" Raph chokes on his freshly cracked can of Orange Crush. "I cannot imagine that there exists a version of myself who is not eager to see his sons safe in their own beds. Do you have a plan to return them home?"

Donnie's stress-drawn face grows even more pinched. "That depends on your definition of a plan," he says, and holds out one of the broken portals.

Splinter takes the innocuous silver disc with an inquisitive sniff and turns it over between his hands, eyes round at the surprising weight of it. "Fascinating. Now come, you will have to tell me more of your adventure. Let us sit together in the garden and talk. I sense that I will need my plants' calming influence to fully process this tale, and there should be tea enough for all.

"But not you," he clarifies, jabbing one long, clawed finger at Don. " _You_ are going to bed."

Don raises an eye ridge and folds his massive hands defiantly across his plastron. "And _why_ would I have to—"

Splinter lifts one palm in a polite request for silence. "In your universe, am I your father?"

Don looks taken aback. "Yes, but... I mean, with Leo _gone_ and you so, _so_..."

"Ah," Splinter says, nodding gravely. "I see."

Mikey furrows his beak, thoroughly confused by this brief exchange. His brothers are equally open in their befuddlement. With a knowing glance at Don, Splinter turns to address the rest of his sons.

"There will come a time when, though you remain my sons, I will not hold the same authority as your father. A time where you are grown and tasked with your own destinies, where—though I hope to retain your respect as counsel—my preferences can only be offered up as requests and opinions. Where any compliance with my will on your part is not obedience, but the reasoned agreement of an adult."

He turns back to Don. "Am I your master, also?"

Don's arms drop to his sides, feet snapping together and shoulders square as he dips forward at the waist. He blinks rapidly, as if startled by his own reaction. "Always," he says thickly.

Splinter nods curtly. "That, then, is an entirely different matter." He draws himself up to his full height, tips of his ears barely clearing the top of Don's head. "As your master, in this world or another—" He points dramatically towards the sleeping quarters. " _Lie_ down before you _fall_ down, child."

If Donnie's earlier explanations about the relationships between their timelines is correct, when it comes down to raw years Don might actually be _older_ than their sensei, with all the martial arts training to match, but Mikey's not going to be the one to point that out. Especially when ordering any version of Donnie to bed _actually seems to be working_.

Good thing Mikey's already put extensive forethought into the question of where to _put_ two extra Donatellos.

"They can bunk in our room," he beams. "Me and Raph will crash in our old beds, it's cool. Plus it's not like they'll take up much space."

"Hey!" says Dee indignantly. He's roughly the same height as Don, but without the shoulders and nutcracker-worthy jaw to match.

"No offense, _little_ bro!" He wonders, as he flings his arm around Dee's slim frame and draws him in for a noogie, if this is what Raph feels every time he calls him squirt or makes him jump for the remote or teases him about barely clearing six feet. He's definitely starting to get the appeal. "Remember: it's not the size of the turtle that counts, it's the motion of the commotion!"

Dee makes a face. " _Gross_ ," he grumbles, his broad, pink tongue curled in disgust. Mikey's chest swells with delight.

* * *

Don sleeps for seventeen hours straight, that first night.

By the time he emerges—looking slightly less dead and significantly more alarmed to realize his impromptu trans-dimensional vacation _wasn't_ just a figment of his sleep-deprived brain—Donnie has finished giving Master Splinter the long version of how they managed to pick up two stray versions of himself, Raph has walloped Mikey twice for the crime of "existing too loudly" within fifty feet of their bedroom, and Dee has put a significant dent in both their chalk and instant coffee reserves scrawling out an exploded schematic of the portals' interiors and the necessary multiverse-compatible amendments to Newton's laws that govern their inner workings along three of the four walls of the dojo.

"It's simple, really," he explains, pupils slightly out of focus and bouncing erratically on the balls of his feet. "Well, as simple as something with enough parts to build your own fighter jet can be. Most of the components are relatively easy to fix once you crack it open, but cramming them all back in is a different basket of sewer apples. Physics is totally bonkers in Dimension X, and their engineering reflects that. Kraang portals _look_ small, but that's only because a secondary artifact of the portal mechanism itself allows for a preternaturally enlarged interior."

This part, Mikey totally gets. "Oh, like Doctor Who?"

"What?"

"Doctor Who! Y'know..." He sketches a rough rectangle in the air. "British dude with the flying telephone booth that's bigger on the inside than it is on the outside."

Dee blinks at him in mild confusion. "You mean Professor Why?"

"Who?"

" _No,_ I said—"

" _Anyway_ ," Leo interrupts, his eyes slightly crossed but his shoulders squared in a determined effort to appear as if he understands more than an eighth of what the extra-energetic and gap-toothed version of his brother is saying. "What's the part you think is _actually_ broken?"

"That would be this." Dee jabs his bo at the pink hexagon drawn double size at the center of the diagram. "It's the equivalent of a Kraang Duracell. And I have no freaking _idea_ how it works."

"So why not just replace it with a human Duracell? I mean, a battery's a battery, right?" April looks less confused than Leo, but then again her poker face—honed by years on-air morning news bullshit—is the stuff of legends. She'd been surprisingly chill, all things considered, to learn of the existence of what Mikey's dubbed "Los Tres Donatellos."

Dee's reaction to meeting _her_ , on the other hand, had been decidedly the opposite, but hey, Mikey's been there. He totally understands.

"Y-y-yes! Absolutely! I mean, _no_. Kinda?" Dee shuffles awkwardly from one foot to the other, teeth bared in what Mikey _thinks_ is meant to be a charming grin. "Well, juice is juice, but the kind of power we're talking about runs counter to the thermodynamic laws of _our_ universe. Uh... universes. Presumably. I haven't really had the time to... _Point being,_ in order to get the Kraang equivalent of a AAA you'd have to blackout most of North America. And these portals run on _D_ cells."

Leo takes a long minute to chew this information over. "So what you're saying is, we'd need an Earth battery the size of the moon."

"Not _quite_ that big," says Dee. "Maybe like, half a moon. But you'd need two of them so _technically_ —"

Donnie lets out a quiet giggle of despair, the calloused heels of his hands rasping faintly as he drags them back and forth across his thighs. His earlier excitement to dig his fingers into a heretofore unencountered machine has been tempered significantly in the wake of what Mikey recognizes all too readily as input overload. It's not so much the number of components crammed into something the size of a slightly squished hamburger that he's stuck on, but the literal impossibility of their various sizes. If the helpfully provided scale of Dee's drawing is to be believed, more than a few of them put the garbage truck's carburetors to shame, while the all-important, all-powerful space battery is smaller than a kumquat. April pats his arm comfortingly.

"This might be a dumb suggestion," she says to Dee, "but are you sure we can't just plug them into a flux capacitor and wait around a clock tower for a thunderstorm?"

"Not if you want to actually go anywhere," Dee sighs. "Not a bad idea if your goal is to turn yourself into a pile of ashes, though."

Leo leans back, beak tilted up towards the ceiling in thought.

"So what we _really_ need," he says slowly. "Isn't a _substitute_ , but an actual _replacement_."

"Direct from the manufacturer," Dee says gloomily. "Do not pass go, do not attempt to file claims outside of the warranty period."

"Well good thing we destroyed all the components of _our_ Krang's portal to make sure they never fell into the wrong hands," Donnie mutters darkly, rocking slightly as his palms push harder and harder into his thighs. "No reason to think _that_ might come in handy further on down the line. All those spare alien parts, what would we _ever_ need with those? No, no, Donatello, better smash them to bits just to be _safe_. I'm sure you'll never ever _ever_ regret—"

"Actually," Leo drawls, something suspiciously like smugness dawning slowly across his face. "I think we have _exactly_ what you need."

Dee blinks at him uncertainly. "You do?"

"We do?" Mikey echoes.

Donnie jerks, as if struck by lightning, and leaps to his feet, eyes wild. "We _do!_ "

* * *

They, in fact, do.

The giant sphere of the Rose Center for Earth and Space gleams softly below them, a blue pearl encased in an oyster of glass. From their perch on the adjoining American Museum of Natural History, their target is just visible amidst the cluster of exhibits at the sphere's base, black and hulking and seemingly of this dimension.

Don leans on the roof ledge and turns his face into the warm wind, the long tails of his mask whipping behind him. As if his first marathon snooze fest wasn't enough, he'd napped that afternoon while they planned their heist, curled up in the pillow-infested corner of their oversized couch that's usually reserved for April. He looks all the better for it, the whites of his eyes actually _white_ and his grip steady where it curls around the light grey stone. He gazes out over the glittering skyline with the air of a septuagenarian on a pleasure cruise. All that's missing is the shuffle board court.

Dee, on the other hand, looks like an overenthusiastic Ghostbusters cosplayer with a serious cyberpunk fetish. He hasn't shut up about the goggles and portable computer rig Donnie loaned him since they first left the Lair

"This is _amazing!_ " Gesturing wildly, he wavers slightly on his feet, still not used to the higher center of balance. "So many data points in such an efficient tactical dispensary! I might never take it off!"

"Donnie sure don't," Raph grins. He nudges Don with his elbow—far softer than he ever has with Mikey. "You want in on this action, Don? You three could form a club."

"No thanks," says Don. "Believe it or not, it's nice to be unplugged for once."

As for Donnie, he's got no choice but _to_ unplug. He's sitting this mission out, Master Splinter skillfully bundling him off to his own bed with an unyielding barrage of tutting and low mutters under his breath.

"There's the skylight we went through last time," Leo says, pointing to a far corner of the roof. "Watch out for the security grid—it's surprisingly tricky. Donnie said they still haven't cottoned on to the meteorite being tampered with, though, far as he could tell."

"Too bad for them," Dee says, reaching up to adjust his goggles from surveillance to tactical view. He's grinning so hard his cheeks might actually crack. "Because with isotropic signatures like _these_ , we're taking the whole neutronium kit and caboole."

This, unfortunately, proves easier said than done.

"Holy cannoli!" Raph gasps. "The fuck is in this thing?"

"About thirty tons of super compressed extra-dimensional engineering," Leo huffs, neck muscles popping as he shifts his grip to a better position.

Raph's eyes look like they're about to pop out of his head. "How the—"

"There was a lecture," Mikey grunts. "You missed it."

Dee, in what is undeniably an attempt to prove his own mutated mettle, struggles not to drop his admittedly much smaller corner of the rock. His manic, mad-scientist laugh from earlier has taken on a desperate, beleaguered breathlessness. "Darwin's beard! Is the solution for _everything_ in this dimension to just scale up?"

"More or less," Leo puffs.

"Right turn coming up!" calls Don from his position on point. "Street exit is in sight! I've already disabled the cameras and alarm, so you can make a straight shot from there."

They scuttle awkwardly through the turn, four pairs of feet squeaking in rapid staccato against the polished marble floor. Their original plan to haul the meteorite back up through the skylight from whence they came had been quickly abandoned once they realized just how goddamn _heavy_ the thing was.

"How the hell are we going to get it to the truck?" Mikey asks breathlessly as soon as they clear the building. Even if they _could_ carry it unspotted down the busy sidewalks of Central Park West, the two blocks between the museum and the disused alley they'd parked in might as well be two hundred, with the rate they're going.

"That's where I come in."

Dee drops his end of the meteorite in surprise, leaving Mikey, Raph, and Leo to stagger beneath the sudden redistribution of weight.

"Who the hell are you?" he demands, bo out and feet braced for a fight. Don appears instantly at his side, expression grim and his own bo brandished threateningly against the half-dark.

A figure detaches itself from the shadows of the arched entranceway, broad-shouldered and undeniably human, face hidden beneath a battered white mask and a long weapon dangling loosely from one hand.

"Donnie's been monitoring your progress through remote cam feed. Called me in as backup." A pale hand touches the top of the mask in a rough salute, then pulls it back to reveal the boyish grin of the man beneath. "Casey Jones, at your service."

This time it's the usually-placid Don who snorts in disbelief. "Oh you've gotta be kidding me."

Dee looks equally unimpressed. " _Great._ And just what are you going to do, Jones? Beat back any curious onlookers with your hockey stick?"

"Not tonight," Casey says smugly, patting the duffle bag slung over his left shoulder. "Not when I've got my little secret weapons in here."

Despite themselves, Dee and Don look briefly intrigued.

With a dramatic flourish and a smirk too handsome for this world, Casey unzips his duffle, plunges both hands inside, and pulls out his patrol hat and a roll of crime scene tape.

Don looks at Dee.

Dee looks at Don.

"I don't see what's so funny," Casey mumbles, tying off the end of the tape and shuffling backwards to unspool it across the street to create a temporary and thoroughly illegal parking zone.

"Me neither," Mikey admits with a shrug. Don and Dee collapse into each other's arms, only remaining upright through an immense collaborative effort as they howl and sob with laughter. "But whatever it is, I think I'm cool with it."

* * *

"I can't believe they _banned_ me from the lab!" Dee seethes, Mikey's well-loved vintage He-Man comforter tucked indignantly under his chin.

"It's nothing personal, brah." Stretched out sideways across the top bunk, Mikey rolls his sucker from one cheek to the next and flips the page of an only-slightly-waterlogged _US Weekly_. "There's no stopping Dad when he gets an idea in his head, and his idea is that all Donatellos need to get some actual _sleep_ now and then. And now it's your turn, since there's no way he can wrangle the three of you into bed at once."

Dee twists restlessly beneath the covers. "But I'm missing the _tear down!_ I'm the only turtle who has half a _clue_ of what we're even supposed to be looking for, and I'm stuck _here!_ " He gestures at the night-light lit bedroom around them, sneakers, airplanes, and all. "With a _babysitter!_ "

"Hey!" Mikey protests, wounded. "I resent that!"

"Prison guard, then," Dee mumbles with a wave of his hand. Mikey peers at him suspiciously, the memory of Don almost pissing himself and Dee's increasingly hysterical laughter when Casey had changed into his uniform and started directing traffic still fresh on his mind, but shrugs and decides to accept the label as an upgrade.

Dee glowers at the ceiling and its scattering of glow in the dark stars and dinosaurs. "Of course, this could turn out to be nothing but an exercise in futility if the batteries aren't compatible. There's no guarantee that the Dimension X of this universe is in any way similar to the Dimension X of mine. It's a multiverse within a multiverse."

"Tell me about it." This issue's Who Wore It Best featurette is a serious disappointment. What is it with humans and their fear of _accessories?_ "It's like one of those little Russian dolls."

Dee clicks his tongue dismissively. "Not really. That would imply a series of progressively smaller multiverses tucked one inside the other, each a simplified copy of the one before it. While there are similarities between us, there's no pattern within the differences to suggest that any one of us is the source reality from which the others are copied. More like we're mirrored shards of a larger whole existing simultaneously, able to reflect independently but only because of the properties of the original universe from which we've been broken."

"Oooh, gotcha! Like, time cube universes or some shit."

Dee slowly turns to stare at him, red eyes going round with alarm.

"What?" Mikey wipes at his mouth reflexively. "There something on my face?"

"Why are you doing this?"

"Doing what?"

Dee licks his lips, shoulders hunched as if braced for a blow. "Listening to what I have to say."

Every conversation with Dee is a new lesson in heartbreak. "See, you keep saying things aren't all that messed up where you come from, but then you gotta go and drop a bombshell of sad town like that."

"It's not..." Dee has this way of blushing that makes him look disturbingly like an anime character. "It's just the way you all _are_ , over there."

"Well, it's not the way _I_ am. Or Raph, or Leo." He pauses, reconsiders. "Okay, yeah, Leo can be kind of a huge butt sometimes, and Raph and I ain't exactly perfect. But we _try_ , is what I'm saying."

Dee twists the comforter between his hands uncomfortably. Unlike Donnie, he looks older without his mask, the space between his brows deeply creased with worry lines. "It's not that I don't appreciate the effort, but I know how boring it can be to listen to be prattle on and on about technical stuff. You don't have to fake interest for my sake. "

"Dude, I'm _not_ faking it!"

Dee rolls his eyes, but there's something desperately hopeful in the way his fingers clench all the tighter around the edge of the blanket. "Sure, sure. Do you even understand half of what I'm saying?"

"Not really," Mikey admits, though he's quick to clarify as Dee's guarded disbelief sags into genuine disappointment. "I mean, theoretical astrophysics isn't Donnie's main thing. He's no slouch at it, don't get me wrong, but he mainly keeps up with it because of all the weird shit we run into. But he's been _obsessed_ with electronics since before he could talk. Kinda hard not to pick up some stuff through osmosis."

Judging by the faint crinkle of his beak, Dee's doubt is not assuaged in the slightest. Undeterred, Mikey slips the rest of the way off the top bunk and plops heavily onto the mattress below. "Go ahead," he grins, arms spread boastfully. "Ask me about transistors."

Dee sighs, red eyes lifting briefly surfaceward. " _Fine_. What's the most basic type of transistor, then?"

"A bipolar transistor," Mikey rattles off automatically. "That's a transistor that uses both kinds of charge carriers."

Dee draws back in obvious surprise. "That's... correct," he says slowly. "What _are_ the two types of charge carriers?"

"Electron carriers and hole carriers," Mikey yawns. "C'mon, dude. You don't have to keep pitching me softballs."

"Sorry," he says faintly, voice cracking on the vowels. "Uh... What's the part number prefix for P-channel FETs?"

Mikey has to think about that one. "It's got a two in it, that much I remember. A two and a couple of letters—L, maybe? Something close to L. Donnie had this whole mnemonic that he would rattle off at the drop of a—"

" _Stop it_ ," Dee whispers.

"Stop what?"

" _That_. You're freaking me out."

"How so?"

"It's just..." Dee sucks in a long breath. "I've never seen you read anything thicker than a trade paperback. You don't _know_ that kind of stuff. You aren't _supposed_ to know."

" _Dude_ ," Mikey laughs. "I don't know if you've noticed, but Donnie is, like, _blind_. We didn't find specs that were halfway _close_ to his prescription until we were maybe seven or eight. Whose job do you think it was to read him all his _Build Your Own Thermo-Nuclear Switchboard_ books until then?"

Dee blinks at him, brow furrowed. "Yours?"

"No, _ours_. Because that's what brothers _do_. And a _friend—_ " He gestures dramatically at himself. "—likes hearing you talk about things you dig. Or I do, at least."

Dee is quiet for a long, long time, red eyes fixed on the plastic starscape above. "I don' think I've ever really had a friend," he confesses at length. "Not by that definition, at least."

"Seriously? What about April?"

That anime blush of his is seriously out of control. Mikey sighs, shakes head in amusement.

"You've got a lot to learn, little brother."

This earns Mikey an unmistakable glare of annoyance. "How many times do I have to repeat myself? I'm _older_ than you!"

Mikey crunches down on his sucker and starts working on the gum inside. " _Psssh._ Being the little brother has nothing to do with age!"

Dee gives him a Look with a capital L—an expression apparently universal to all Donatellos—so Mikey clarifies.

"Well, okay, it has to do with age a _little._ But according to April, between all our clutches the four of us hatched maybe two weeks apart, _max_. How much difference does that really make, long term?" The mattress creaks beneath him as Mikey leans back and settles into his groove. "See, being the little brother is a state of _mind_. It's not just being the spoiled, bratty one, the one who gets to goof off with the least repercussions in exchange for always going last in Monopoly. It's about letting yourself be open about the things that scare you, about not being afraid to whine and demand attention when you need it, to let yourself relax and have fun and tease because you _know_ you've got a bigger brother watching your shell, teasing right back."

Dee's jaw is locked, the muscles of his neck and shoulders practically vibrating beneath the strain of the unnamable emotion swelling inside of him. Donnie doesn't like to be touched when he gets like this, but Dee's _not_ Donnie, is he? Slowly, eyes peeled for the first sign of objection, Mikey reaches out, hand seeking the lump in the covers he suspects is Dee's knee, and gives it his best, most earnest, big brother squeeze.

"So things are kind of shit for you back home. The kind of shit you've gotta fight to hide from everybody, including yourself, because you've got no clue on how to make them _un_ -shit. Well newsflash, Dee: you're _here_ , not _there_. So let us spoil you a little, okay?"

What little fight is left in Dee escapes him in a long, whistling rush of air. He sags into the pillows, limp as a wet noodle.

"Mikey," he mumbles dazedly. "When the hell did you get so _smart?_ "

Mikey beams his most triumphant beam. "Dude, I _told_ you. The Mikester is the total package.

"Now shush," he continues, leaning forward to pull the comforter higher under Dee's chin. Pulls out the moth-eaten teddy bear he's been hiding down the back of his sweatshirt and makes it kiss Dee on the head before tucking it snugly beside him if only to see the flare of indignant fury light up Dee's exhausted face. "Warden says it's night-night for little Donatellos."

* * *

Donnie's not in any of his usual spots, and with a project as complex and weighty as rebuilding two alien thingamabobs resting on his shell he's not likely to make a solo trip to the surface, which means there's only one logical place to look for him. Mikey's not quite tall enough to climb the tangle of pipes stretching up and up until they vanish into the dark of the Lair's highest levels hand over hand the way Raph and Donnie can, but whatever. It's more fun to jump, anyway, especially with the added challenge posed by his precious cargo.

"Knock knock." It's an old joke, and objectively not a very good one, but in a family that's lived most of their lives in a doorless sewer it counts as a classic. "Can I come in?"

Silence for several long seconds, broken only by the distant echo of voices and the faint rush of water through the pipes. Despite rumors to the contrary, Mikey _does_ know how to be patient sometimes, and eventually Donnie's head pops into view, bare-faced and looking oddly naked without his glasses and with his mask loose around his throat. He squints down at him futilely. "Hey Mikey. S'just you?"

"Just me. And this plate of double cheese, double jalapeño, double sour cream, hold the beans nachos." Donnie can't see for shit without his glasses, but he holds the nachos up anyway, waggling the plate a little so the smell of hot cheese and spiced meat wafts upward enticingly.

As predicted, Donnie's nostrils flare inquisitively. "Raph brought me food earlier," he says, but he still reaches out for the plate. Recognizing the invitation, Mikey hops up the last few pipes light as thought and plops down on the far end of Donnie's perch.

This isn't the first time Mikey's found his brother shut away someplace dark and cramped with something mechanical on his lap in times of stress. He knows the drill. And if Donnie's so overstimulated that he's had to all but strip himself of _sight_ , then...

Settling the plate within easy reach between them, Mikey scoops up a chip and leans back to crunch contentedly as Donnie wipes one hand roughly across his pants and dives in.

"Whatcha workin' on?"

"Nothing, really," Donnie sighs, dirty hand drifting restlessly back to the grime streaked part as he licks a stray drip of salsa from his wrist. It's too big to be a component for his computer rig, too oily to be something from the plumbing or air systems. Must be part of an engine, though god knows to what. "Just something to make my brain shut up."

"Gotcha." In the dojo below, Splinter's tail thumps against the floor in a deep, steady rhythm, keeping time as he puts Don though a kata. "So, how much longer were you planning on hiding out up here? Need a bro to run interference?"

Donnie frowns, blind eyes squinting contemplatively at the half-assembled machine. "Not much longer. Just needed a break from myself, in more ways than one."

"I hear ya. Dee's great and all, but he can get a little..." He thinks back to the sound Dee had made when Donnie had presented him with a vial of medical-grade mutagen to play with, the high-pitched, gleeful cackle drowning out the rest of Donnie's explanation on how to use the equipment he'd stolen from the burnt out remains of Sach's lab to harvest a sample from his own blood for comparison. "...excitable."

One corner of Donnie's mouth quirks up in a tired but genuine grin. "Coming from you, that's saying something."

Mikey sputters the obligatory objections to the soft insult and snags a second chip in retaliation. This draws Donnie's attention back to the food exactly as planned, and in less than a minute the plate has been stripped clean of all but a few streaks of melted cheese, which Donnie offers to Mikey in a half-hearted truce. Mikey accepts, expertly licking the plate clean as he watches his brother turn back to the problem at hand. One of the problems, anyway.

"So what's your brain bugging you about? Something with the salvaged batteries?"

"Not really," Donnie groans. "Though not for lack of trying. You know how there's AC current and DC current?"

"Like I know the drums for LL Cool J's 'Rock the Bells'."

"Well, it's kind of like having to wire in a step-down, rectifier, capacitor, and regulator so your stereo doesn't blow up when you plug it into the wall, but times a _million_."

Yeesh. No wonder he's jammed up in the pipeworks with a glorified Rubik's cube to fiddle with. Something tells Mikey that that's not what's _really_ at stake here, though so he waits until he's eventually proven right.

"What do you think about them? Not—" Donnie waves vaguely downward. "—just _me_ them. _You_ them. Raph and Leo them."

"What about 'em?"

Donnie lifts one shoulder in a half-hearted shrug. "Don's had a hard couple of years. Leo— _his_ Leo—basically vanished, leaving him in charge. Their Splinter is _dying_ , the kind of dying no amount of mutagen can stop. Raph's refusing to take any of it well, while you're stuck riding it out somewhere in the middle. And Dee..." He trails off uncomfortably, fingers twisting and twisting around two stray jutting bolts. "They call us the _B_ _Team_ , there."

"Yeah," says Mikey darkly. "Way rude."

Loose, tight. Loose, tight. Donnie doesn't look up from the machine in his lap. "Do you think that could ever be us?"

Brothers in blood, but not in action. A constant, unending struggle for rank and recognition. Lessons learned only to be immediately forgotten, the Lair an empty, echoing space with rooms that pulled apart instead of mashed together.

Mikey thinks about it.

"Nah."

Donnie's twisting fingers pause. He tilts his head, gazed directed somewhere just past Mikey's left shoulder. "Why not?"

Mikey shrugs and swipes another chip. "It's just not the way we're written. Like, down in our DNA and stuff."

"Hmm..." Donnie looks thoroughly unconvinced. "Didn't expect you to fall on the 'nature' side of the debate."

 _Shit_. It's been a while since they've gone though any developmental psychology and Mikey is _not_ prepared to win this argument on that front. He scrambles to recover. "Look, I'm not saying that we're not capable of our _own_ uniquely spectacular screw-ups, but when it comes down to it—"

Leo chooses this moment to poke his head between the pipes. "Sorry to interrupt. Just looking for a quiet place to read." He nods down at the battered paperback tucked into the chest strap of his scabbards. "It alright if I climb on through?"

His head is turned towards Donnie, but his eyes flick sideways to catch Mikey's. Mikey mouths a silent answer to his unspoken question.

Donnie doesn't speak but does lift his knees to give Leo room to pass. As if this was some sort of cue, Raph's bandanna-wrapped noggin appears in the space recently vacated by Leo.

"Never should have told that kid how to work Sach's shit, Donnie," he grumbles. His arms are covered in Band-Aids from multiple needle sticks.

A voice from the dark above, scuffing sounds as Leo stretches out on a long span of pipe. " _Technically_ that kid is—"

"I know, I _know_." Raph has to wiggle slightly to fit his bulk through the narrow gap. "Any room up here for one more pigeon?"

Donnie hesitates, bare arms tense beneath long streaks of grime like a cat shying away from too much petting, but after chewing on the thought for a moment longer he settles again. "Yeah," he says, muscles relaxing. "Plenty of pipe for everyone."

Mikey's far from stupid, but he can be kind of oblivious sometimes. Can get so wrapped up in his own excitements, his own small joys, that he overlooks opportunities, misses vulnerabilities in his opponent's form, fails to see how one calculated strike _here_ and a quick slice _there_ is all that's needed to crumble those defenses.

This, however, is not one of those times.

"Hey Raph. We're family, right?"

"Yeah. _Thankfully._ " He sneers at him like it's a joke, but there's no hiding the hard vein of relief poorly buried beneath the sarcasm, the edge of sadness rimming his gaze as he looks back over his shoulder down into the Lair below.

"There you go." Mikey spreads out his arms as if that explains everything. "Turtles forever."

Raph yanks at his mask tails as he passes, climbing over him to wedge himself in the dip of an oversized U-bend. It doesn't hurt, but when has that stopped Mikey from kicking up a fuss?

"Right," Leo rumbles commandingly from above, kicking out softly with one foot to silence the worst of Mikey's cartoonish whining. "Turtles forever."

And yeah, it sounds kind of dumb when he says it, especially when he uses his "Fearless Leader" voice, the one that makes him sound like Captain Kirk in an after school special, but it also sounds kind of awesome. Sounds like something solid they all can stand on, a touchstone to keep in their pockets, a lighthouse beacon cutting through the fog of self-doubt, all for one and one for all.

Donnie ducks his head, chin tucked under the rim of his plastron, but it's not enough to keep Mikey from seeing the smile creeping slow across his dark cheeks. They each settle back into their perches: Leo lost in his book, Donnie found in his machine, Raph licking his wounds, Mikey picking the last microns of cheese from the plate. A sudden crash from below makes Mikey's fingers jerk towards his nunchucks—out of the corner of his eye he sees a similar ripple of alert movement flow through Leo and Raph—but Donnie barely blinks, safe and secure behind his semi-circle of sentries.

In the streets, they are warriors. In the dojo, they are students. In a lab, once, they were experiments, _animals_. Creatures granted no value beyond what could be taken from them and given to others.

But here, in the pipes together, they are four, they are one.

They are _brothers_.

* * *

That's the funny thing about time. It's all relative, from what Mikey's read. Or what he's read to Donnie at least, when neither of them can sleep and the other's eyes ache too much from long hours squinting at the glow of a computer screen to make heads or tails of tiny paperback print. It's all dependent on your perspective, on where you are and how fast you're going and whether or not you've got something else in easy view to compare yourself against.

Thus, on the day when Donnie finally walks into the living room, both portals cradled in his hands like delicate bombs, part of Mikey insists that it's been weeks, another seconds, since they stole Don and Dee into their lives. Both are wrong. Both are right. The multiverse is weird that way.

"Well," says Donnie with cautious finality. "I think that's it."

At the ping pong table, Raph overswings and completely misses Leo's serve. Dee and Mikey are spread out in front of the TV with their sketchbooks, squabbling good-naturedly over a pack of colored pencils. Don is kicked back on the sofa with April, Casey, and Splinter, the last of his frightening gauntness finally faded and eyes unshadowed as he laughs easily at the sitcom on the screen. All eyes turn to Donnie with faint surprise.

"You fixed them?" asks Raph.

"Theoretically. It's always possible that I've accidentally rigged them to explode."

"Huh." There's an awkward moment where Don and Dee don't exactly leap to their feet with excitement. When they _do_ drag themselves to a standing position, there's a frenzied, silent debate between them on who will be the first to grab his respective portal from Donnie's proffered hands, a debate both seem eager to lose.

Don's face is still as stone for the first time in days (weeks?) as he examines the seemingly harmless portal, old shadows settling back into their once-familiar hollows. Donnie's done a good job; there are no stray wires or grafted on parts, the portals gleaming with the same smooth, alien silver they had on that fateful night when they'd realized they were not quite as unique as they'd thought they were. "Does that mean this is goodbye?"

"I... I-I don't..." Dee stares down at his own portal with wide, panicked eyes. "I mean—what if it they don't _work?_ "

"You can stay." There's no hesitation in Leo's answer. "We'll take care of you."

"What if they _do_ work?" Don ads, his own fear equally naked.

Leo looks to Donnie. Something unspoken passes between them.

"You can still stay," says Donnie, voice quiet but unyielding as iron. "If that's what you want. It's up to you."

"Whatever, dudes!" Mikey ads, arms thrown open in welcome. "The more the merrier!"

All eyes turn to Raph.

His mouth fumbles for a long minute around what looks like an eloquent, heartfelt speech, if only the big softy had the strength to voice it without crying.

"Yeah," he eventually chokes. "You... _Yeah_."

Don turns to Splinter, eyes wide and slick with a silent entreaty for guidance. The old rat simply nods his head, smile soft and permissive. "A father has love in his heart for all his children."

"You'll always be family," April chimes in. Behind her, Casey nods in agreement. "No matter where you are."

"I..." Finally, finally, Don looks to Dee. "What do you think?"

The silence that fills the Lair is too thick to be cut by even Leo's obsessively sharpened blades. Dee turns his portal slowly between his thick fingers, tongue darting nervously in and out as his pale face twists and frets beneath a storm cloud of indecision.

Dee looks to Donnie, to Mikey, to the rest of their family, patient and ready to accept whatever his choice may be.

"Only one way to find out." He sucks in a long, shuddering breath. Blows it out again. Lifts one finger over the ominously glowing pink button.

"Here goes nothing."


End file.
